The use of wood pulp for paper-making ..

TS

UC-NRLF

READ BY

S. CHAS. PHILIPPS, M.S.C.I.,

ON

THE USE OF WOOD PULP FOR
PAPEIHIAKIM.

( Extracted from the Journal of the Society of A rfe, Vol LlUf
May 19th, 1905.)

YD 03880

E OF THE SUPERINTENDENT OF GOVERNMENT PRINTING, INDIA,
1Q05,

PAPER

READ BY

S. CHAS. PHILIPPS, M.S.C.I.,

ON

THE USE OF WOOD PULP
FOR PAPER-MAKING.

(Extracted from the Journal of the Society oftArts, Vol. LIII,
May i gth, 1905.)

CALCUTTA:

OFFICE OF THE SUPERINTENDENT OF GOVERNMENT PRINTING, INDIA,

1905.

X

Extract from the Journal of the Society of Arts, Vol. LI II,
May /p,

THE USE OF WOOD PULP FOR PAPER-MAKING.

BY S. CHAS. PHILLIPS, M.S.C.I.

TTwas with peculiar pleasure that I accepted the compliment you
^ were good enough to pay me, when you invited me to read a paper
on the subject of " Wood Pulp." I have been reminded of the fact that
there are in this Society many members who have no practical acquaint-
ance with paper-making or with the subject I am trying to deal with
to-night, and, therefore, I hope to avoid technicalities as much as possible,
although I think you will readily see it is necessary in a paper of this
kind to deal in a general way with the evolution of the wood pulp
industry, and particularly in its application to paper-making, and in this
connection, to deal historically with the progress of pulp- making, and
its chemical treatment. • I think, perhaps, I need scarcely say at the
outset, that in the cheaper forms of paper, as we know it to-day, the
raw material is substantially wood. I am aware that if you were to ask
" the man in the street " of what paper is made, you would probably be
told "rags"; but although that used to be the case, the use of paper
to-day is so extensive that it would be impossible to meet the demand for
one-thousandth part of the total consumption, if the paper-maker had
to rely on rags, and I think I may here say that it is due to the engineer
and to the chemist that we owe our cheap Press, and largely to the fact
that wood has been taken full advantage of in its application to paper-
making. For reasons which I may refer to later on, it is obvious that
although England holds its own very comfortably at present as a paper-
making country, it is not at all probable that Great Britain will ever

A

a ' '• • : :..:•» .„ * USE OF WOOD PULP

produce wood for paper-making on a commercial scale. Not long ago,
one of our leading paper-makers, whilst referring to this subject, observed
that we might hope to make wood pulp here when we had the water-
falls and timber forests of Canada, Norway, or Sweden. There was a
great deal of truth in that remark, and although there are gentlemen who
are sanguine that we might make very much more use of our forests and
unproductive land than we do, that we might turn it to good account for
timber growing, I do not think that for practical purposes we need, at
the present moment, take that into consideration. We may (and I am
speaking from practical knowledge) dismiss Great Britain out of the
calculation when we are dealing with the great countries which are
providing us with timber for the production of wood pulp, and are likely
to do so for very many years to come. It may, I think, be said, roughly,
that the wood-pulp industry has established itself and attained its present
position during the past quarter of a century. There was a time within
my own recollection when the manufacturers of high grade papers in
this country looked askance at wood, and I know of a gentleman in the
wood-pulp business who told me that about twenty years ago when he
waited upon a well-known Maidstone firm, and tried to induce them to
give a trial to good chemical wood pulp, the owner of the mill was very
rude to him, and almost ordered him away from the place. But times
have changed since then, and at the present moment many of the mills
which in the early days of wood pulp derided its possibilities would not
hesitate to place a very large order for the same, at what they might
consider a reasonable price. To those who are uninitiated in what I
may term the elementary details of the wood-pulp industry, it may be
necessary to mention that for the purposes of a paper of this kind, we
must bear in mind that there are, to put the matter broadly, two methods
of transforming raw wood into pulp.

MECHANICAL AND CHEMICAL.

I have, I may say, travelled a great deal in the principal pulp-
producing countries, particularly Sweden, Norway, Finland, the United
States, and Canada, visiting the most up-to-date mills where all classes
of wood pulp are made, and so have had excellent opportunities for
studying and comparing the various processes now in use. Sweden and
Norway are countries from which we have for years derived our prin-
cipal supply of WQpd fibre for paper- making. Years of practica.1

FOR PAPER-MAKING. 3

experience have taught the Scandinavians to produce the best wood
pulp in both mechanical and chemical varieties ; but although both
Sweden and Norway claim to have enormous forests of pulp wood, yet
in spite of the law in Sweden which compels the replanting of six
saplings for every tree cut down, it seems to me that at the rate at
which the forests are being denuded of their timber for other purposes
besides the conversion into wood pulp, in less than twenty-five years
from now the maintenance of the timber supply will become a grave
question. While in South Germany timber fit for pulping can be grown
in fourteen or fifteen years, in Scandinavia it takes about forty years.

During the past dozen years our great Dependency in the Western
Hemisphere, viz., the Dominion of Canada— of which our distinguished
Chairman, Lord Strathcona and Mount Royal, is the representative in
this country— has come forward as a pulp-producing country, much to
the relief and satisfaction of British paper- makers ; for, with the growth
of Canadian competition, it has become an important factor in keeping
the prices of pulp from Sweden and Norway from being advanced higher
than was justified in normal times. So that the advent of Canada into
the wood-pulp business is likely to have a steadying influence in the
matter of prices. I am pleased to say that Canada is making great
progress in the industry by the construction of new mills, and the exten-
sion and improvement of existing mills. Our Chairman (Lord Strathcona)
takes a keen interest in the wood-pulp industry of Canada, and has been
largely instrumental in its development. As a frequent visitor to
Canada, I trust that the Canadian Government will not be long before it
adopts the replanting system of Sweden and Germany. At present
there is but little attempt to protect the colossal and magnificent forests
of the great Dominion of Canada, which are the envy of the whole
world. What with the enormous wastage that goes on, and the serious
inroads made by forest fires and indiscriminate cutting, Canada will
have to take speedy steps to take care of the magnificent and great
wealth which Nature has endowed her with in her forests, or otherwise
she will, long before the present century closes, be bereft of that grand
birthright.

In an essay published by Reaumur in the eighteenth century there
is a suggestion that it might be possible to make paper from wood, and
in 1750 paper was made from the bark, leaves, and wood of various
trees in France. TJie class of wood generally used for the manufacture

A 3

4 USE OF WOOD PULP

of chemical pulp is known as soft wood, and belongs to the order
Coniferae, or cone-bearing trees. The common spruce and the silver fir
are the chief species that supply the chemical pulp of Europe, while
the white spruce, black spruce, Canadian Hemlock, white American
pine, and the silver fir furnish the bulk of wood pulp in America. For
mechanical wood pulp, poplar, aspen, spruce, and fir are mostly used.
Although almost every class of wood can be converted into pulp, only
the soft coniferous trees are economically suitable. Trees having a
diameter of from 6 inches to 20 inches at the base, and of about twenty
years' growth are considered best. Smaller logs are not so economically
worked, and larger timber is usually cut for lumber. Within the
last few years a great number of pulp mills have been started in the
southern and western States of America, and other parts of the world,
which, in order to utilise the particular class of wood growing in those
districts have adopted somewhat special methods, and we now find
wood pulp being produced from a great variety of woods. The great
majority of pulp mills obtain their supply of wood in the form of round
logs about 6 to 10 feet long, while many in the lumber cutting districts
use edgings and other waste wood from sawmills.

Sawdust has also been experimented with for the purpose of produc-
ing chemical fibre, but owing to the difficulties of getting the solvent
liquor to circulate readily through it, and other troublesome features, it
has been found to be impracticable. Shavings would be more suitable
for converting into wood fibre, and are employed by some, although
their bulkiness prevents any substantial weight being dealt with in
each boiling operation. They might, however, be more conveniently
used if they were first put through some form of machine similar to a
hay-cutting mill, and reduced to small lengths.

Like ordinary lumber, the logs employed for pulp-making are
generally cut by gangs of woodmen, who camp out in the forest during
the winter months. In the early spring, when the snow and ice begin to
melt, the logs are easily conveyed to the banks of the river, which, being
at this time naturally swollen, carries them down to their destination.
The log-driving men's duty is to keep them off the banks, and clear of
obstacles, until they reach the saw or pulp mill, where booms, consisting
of a number of logs chained together endwise, are stretched across the
river to prevent them from being drifted any further. By this means
millions of feet of logs are annually brought from the centre of the

FOR PAPER-MAKING. 5

forests down to the mills. The result of being in the snow and water,
and the friction in driving, is such that the logs generally arrive at the
mill with the bark entirely removed.

In Europe, Scandinavia, Russia, Austria, and Germany possess the
largest wood pulp forests, which, in the former countries, are the natural
virgin growth, and still very extensive, in spite of the enormous quantity
annually cut. In Germany the original natural forests have been almost
exhausted, but owing to the wisdom and foresight of the authorities,
they have been replanted and grown under Government supervision.
Undoubtedly the American continent has the largest supply of pulp
wood, but even the extensive forests of the Adirondacks and similar
districts round the large paper-making centres are rapidly becoming
depleted by the pulp manufacturers. The State of Maine and other
New England States have still enormous quantities of uncut pulp wood,
but unless measures are taken to preserve and cultivate them, the
present rate of cutting cannot be indefinitely continued. The immense
virgin forests of pulp wood in Canada and Newfoundland are practically
untouched at present, but the day is not far distant when great
demands will be made upon these forests.

Pulp wood is generally bought by measurement ; the fact that the
amount of water contained in the wood varies so considerably prevents
any method of dealing with it by weight. The method of measuring
timber is also very troublesome and unsatisfactory, more especially by
the tape or quarter-girt system. Measuring in fathom frames is costly
work, and, like pile measurement, varies according to the skill or other-
wise of those piling the logs. In America, wood is generally bought
by the cord, which equals 128 cubic feet pile measurement. In Great
Britain and Scandinavia it is usually bought by the fathom, which is a
cubic pile of logs 6 feet long, and piled 6 feet high, containing 216
cubic feet. In many of the Continental countries it is purchased and
sold at so much per cubic metre.

The appellation, wood pulp, includes two distinct varieties having
different chemical compositions and properties. These are known in
commerce as mechanical or ground wood pulp, and chemical wood fibre
or wood cellulose. The former is simply wood ground, washed, and
made into layers or sheets ; while the latter, or chemical wood pulp, is
produced by treating the wood with various chemicals to remove the
ligneous and mineral compounds, leaving the soft, pliable cellulose fibres

6 USE OF woob PULP"

almost pure. Of the chemical pulps, there are also several varieties,
named according to the chemical solvent employed in the manufacture
• — we have sulphite wood fibre, soda fibre, and sulphate fibre, or pulp
prepared by the action of sulphate of lime, caustic soda, and a solution
of sulphates of soda, respectively.

WOOD-STUFF, OR MECHANICAL WOOD PULP.

Dr. Joseph Bersch, a well-known authority, describes mechanical
wood pulp as wood converted by purely mechanical means into a fine-
fibred mass, which by itself may serve for the production of coarser
grades of pasteboards as well as for the manufacture of various articles.
Its chief use, however, is as an addition to paper stock for the manu-
facture of inferior grades of paper. Although wood stuff, if properly
prepared, is sufficiently fine-fibred to be made into paper in the paper
machine, it is not used by itself for this purpose, because such paper
possesses the undesirable property of becoming darker and acquiring,
in a short time, a brown colouration when stored exposed to the light.
The cause of this phenomenon is, in Dr. Bersch's opinion, found in the
fact that the wood-stuff still contains nearly the entire quantity of
encrusting substance — lignin, etc.,— originally present in the wood, these
substances being subject to great changes. Hence, in the course of
time efforts were made to remove these substances from the wood, so
that only pure cellulose remains behind, which, as it does not show the
already mentioned defects, can be used practically by itself for the
manufacture of paper.

WOOD FOR GRINDING.

Although practically every kind of wood may be made use of and
put into the grinder, some woods are far preferable to others, and of
the European varieties of wood, ash, linden, fir, pine, and birch are
particularly suited for the purpose ; whilst beech may be used, but is
considerably less suitable.

The views on the screen will convey a good idea of the practical
operations.

MECHANICAL WOOD PULP AS MADE IN 1844.

In 1844 there was patented in Germany a machine for grinding
wood for the manufacture of pulp. The inventor, Keller, sold the

PAPER-MAKING, j

patent to the firm of Henry Voelter's sons, who afterwards used the
pulp in the manufacture of " news" paper-

The Voelters made numerous improvements in Keller's invention,
and a quarter of a century after it was patented in Germany by Keller ;
this wood pulp-machine was destined to play an important part in the
United States, when, in response to the demand for the rapid printing
of daily newspapers, the web press was to come into use. The Voelters
— Christian and Henry — made numerous improvements in the machine,
Christian Voelter obtaining patents in various European countries — in
France even as early as April nth, 1847. Henry Voelter patented his
improvement on the pulp machine in Wurtemburg, Germany, on August
29th, 1856, and in the United States on August loth, 1858.

Various methods of treating wood previous to submitting it to the
action of the grinders have been proposed and used. By one process
the logs of wood, after being cut into suitable lengths for grinding are
treated by first steaming them, then removing the acids generated in the
steaming operation, next treating the steamed wood with alkali, and,
finally, grinding or reducing the pieces to pulp. Steaming has been
resorted to for the purpose of removing the bark from wooden blocks
preparatory to grinding the solid parts ; and wood has also been treated
with water sprinkled on it from above, and steam simultaneously applied
from beneath it, in order to soften and cleanse it preparatory to grinding.

But the process which we shall now describe, which is that of
Mr. George F. Cushman, of Barnet, Vermont, is intended to facilitate the
disintegration of the fibres, when submitted to the action of the revolv-
ing stones by a preliminary cooking of the block of wood in a bath of
boiling hot water with lime, soda-ash, or equivalent chemical agent in
solution, to soften the block, toughen the fibres, and lessen their lateral
adhesion. By this process the block is reduced to pulp with much less
power than is required to grind a block not so treated ; and the pulp
produced is claimed to be softer, stronger, and more desirable, since the
fibres are not broken up or comminuted, but are more nearly in their
natural condition, with their lateral beards or filaments preserved, so
that when re-united in the paper sheet special toughness and tenacity
are attained.

In carrying out this method, I believe it is usual to immerse the
solid wooden blocks in a strong solution of lime, soda-ash, chloride of
lime, or equivalent chemical agent, kept boiling hot by the introduction

USE OF WOOD

of steam or otherwise, and adapted to soften the blocks in readiness for
grinding, and retain the blocks under treatment from ten to twenty -four
hours, or until the liquid has had time to penetrate all parts of the block,
and the lateral adhesion of the fibres is so weakened that they will
readily separate by the attrition of the grinding stone without being
broken short or reduced to a mere powder ; and as the chemical action
is most rapid in the direction of the length of the fibres, it is desirable
to cut the block much shorter than is usual, or to form transverse saw-
scarfs at intervals between its ends, in order that the solution may
readily penetrate from each end to the centre, so as to loosen and
toughen the fibres throughout the block. The pressure of steam above
the liquid in the tank tends to force the solution into all the pores of
the immersed blocks ; then remove the blocks from the tank and
subject them to the action of the grinders in the usual way, keeping a
constant steam of water upon the stone, and the disintegration will be
found to be effected with great rapidity, owing to the preliminary
treatment received by the blocks, and also that no washing is required
beyond what results from wetting down the stone. The pulp produced
is claimed to be of superior quality, and as the blocks have absorbed
only so much of the chemicals as is beneficial to the fibre, it is in condi-
tion for the successive steps in the production of various grades of paper
of special strength, and for numerous other purposes in the arts. If
preferred, however, this fibre may be mixed with hard stock made of
other material, such mixture producing paper or board of exceptional
toughness.

VOELTER'S MACHINE FOR CUTTING OR GRINDING WOOD AND
REDUCING IT TO PULP.

The art of reducing wood to pulp by subjecting the same to the
action of a revolving stone is not a new one, machinery for grinding
wood while a current of water was applied to the stone having been
patented in France by Christian Voelter as early as 1847 (see
" Brevets d'Invention," vol. x., second series), and in England by
A. A. Brooman, of London, in 1853 (see " Repertory of Patented
Inventions," for May, 1854, p. 410).

A large number of inventions for cutting or grinding wood into pulp
have been patented ; but the enormous development of the paper-
making industry, and the cheapening of paper during the last fifteen

FOR PAPfeR-MAklNC. £

years are largely due to the general introduction of the machine for
disintegrating blocks of wood and assorting the fibres so obtained into
classes according to their different degrees of fineness, invented by
Mr. Henry Voelter, of Heidenheim, Wurtemburg, Germany, and for
which invention he received letters patent on August loth, 1858, from
the United States

In all the processes known or used prior to Voelter's invention the
wood had been acted upon by the stone in one or two ways, via., either
by causing the surface of the stone to act upon the ends of the fibres,
the surface of the stone moving substantially in a plane perpendicular
to the fibres of the wood ; or, secondly, by acting upon the fibres in
such a direction that they were severed diagonally, the surface of the
stone moving diagonally across the fibres. The first plan, in fact, made
powder of the wood — an obviously unsatisfactory result. The pulp had
no practical length, and on trial proved worthless, or nearly so. The
second plan was carried out by the use of a stone revolving like an
ordinary grind-stone, the wood being applied upon the cylindrical
surface thereof, the fibres perpendicular, or nearly so, to planes passing
through the axis of the stone and the point or locality where the grinding
was performed ; and this plan also failed, because the fibres were cut off
in lines diagonal to their own length, and were consequently too short
to make good pulp. There were other difficulties attending the process
not necessary here to mention. Such was the state of the art prior to
Voelter's invention ; and his improvement in the art consists in grinding
or milling away in detail from the bundles of fibres which make up a
piece of wood by acting upon them by a grinding surface which moves
substantially across the fibres and in the same plane with them. In
carrying out this improvement upon the art Voelter splits a log of
wood and applies the flat side upon the stone, and then the stone so
revolves as to cause points upon its surface to pass the fibres in lines
perpendicular, or nearly so, to the length of the fibre. By this mode of
procedure it is possible to obtain a sufficiently long fibre and save much
power. Voelter's improvement in the art consists, further, in re-grinding
the fibres by causing them, after being separated from the block, to pass
under other blocks of wood, which are being reduced to pulp, upon the
same stone. The fibres torn out at the first operation are thus rolled
over and crushed again and separated into smaller fibre.

16 tJSE OF WOOD

Voelter's improvements in the machinery are in an arrangement of
pockets, with reference to the grinding surface, so as to hold the
blocks of wood in such position that their fibres may be separated from
the blocks in the manner described, and whereby fibres may be
reground, and in a contrivance for feeding up the blocks by a positive
feed instead of by force derived from weights or springs, as formerly
practised ; and a contrivance for causing the feed to cease automatically.

On May 22nd, 1866, Mr, Voelter was granted another patent for
improvement in his machine for reducing wood to paper pulp, which
patent was re-issued on April 23rd, 1872.

BACHET-MACHARD PROCESS OF DISINTEGRATING WOOD.

Messrs. I wan Koechlin & Co. have carried on the Bachet-Machard
Patent at the Isle Saint Martin, near Chatel (Vosges), France, and it
has also been experimented with on a large scale at Bex and at St.
Tryphon, Switzerland. At the start the inventors had in view the
saccharification of wood, the paper pulp being intended to be only a
secondary product of the manufacture of alcohol ; but in practice the
inverse result has been obtained, the paper pulp becoming the principal
product, and alcohol the secondary one.

The wood, previously saun in thin discs, was thrown into tubs, the
filling of which was then completed with water and sulphuric acid, the
latter in the proportion of one- tenth. Each tub would contain 188
cubic feet ; eighteen hours' boiling was needed ; the discs were then
washed as well as possible in order to eliminate the acid, then passed
through the crushers and the mills. Each 31 J cubic feet produced
about 330 Ibs. of dry pulp ; 65 Ibs. of acid and 136 Ibs. of coal were
used for the production of 220 Ibs. of pulp. Calculating the value of
the wood at 38 cent per cubic foot, the cost of production of 220 Ibs. of
pulp would be Ss.

With the Bachet-Machard method a brown pulp is obtained pro*
ducing a good brown folding paper costing about 3^. §d. per 100 Ibs.
dry pulp. This brown pulp is easily transformed by a half bleaching
into a blond pulp costing about Ss. 4^. per 100 Ibs., and this can be
utilised with or without mixing, for the manufacture of wrapping paper
and of all the coloured papers. Up to the present time a method for
economically transforming this into white pulp had not been found
(i. " Dictionnaire de Chimie," Wurtz, tome ii., p. 749, et seq.}.

PAPER-MAKING. t i

The inventors think that the tenth of acid, which they cause to react
at 212 F. upon the wood, saccharifies the ligneous, or rather the incrus-
tating substance without touching the cellulose fibres ; thus the cellulose
becomes easily separated into fibres by mechanical means. It is
probable that the acids modify the incrustating substance and render it
friable, and that at the same time certain principles of the wood are
converted into glucose.

The process is the same as with straw and esparto, when alkaline
washes are used ; but it requires more energetic boiling ; the propor-
tion of alkali is doubled, and the boiling done at a pressure of 165 Ibs.

A little more chlorine is also required for the bleaching. In this
country common " news " requires to have about 20 per cent, of sulphite
to hold it together on a fast-running machine. In America it can be
produced with 100 per cent mechanical, the reason being that mechani-
cal coming direct from the grinders has greater felting powers than if
converted into pulp and shipped to this country. This point is a matter
of considerable economical importance, and probably accounts for the
difference got with fast-running machines between England and the
United States of America.

I have explained that mechanical or ground wood pulp can only be
used alone for inferior grades of paper, and must be used direct from
the grinders on to the paper machines. A combination of about 70-80
per cent, of mechanical wood pulp fibre, and 20 to 30 per cent, of
chemical produce the " news " on which our daily newspapers are
printed.

The manufacture of wood pulp is undoubtedly a most interesting
study which has closely occupied the minds of eminent scientists and
experts for years, and new facts are being brought to light. Indeed,
wood pulp as a field of research, seems inexhaustible.

Quite recently I visited the important paper and pulp mills of the
Munksjo Company at Jonkoping, in Sweden, where the manufacture
of what is termed " Kraft " paper was discovered, tradition says by
accident, although Mr. Hagborg says that the method was arrived at
after long and careful experiment.

Wood pulp is used solely in the production of many thousands of
tons of boards, which are used by bookbinders, paper boxmakers, and
others. I might mention that in the various pulp-producing countries

12 USE OF WOOD PULP

many millions of pounds sterling are invested in the production of pulp.
A large proportion of this is British capital.
Reverting to the question of

GROUND WOOD,

or, as it is generally known in this country, mechanical, it may be said
that the method of logging and of conveying the cut timber from the
place where it falls into the mill, is governed largely by local conditions,
which I shall deal with subsequently. But when once the wood is at
the mill, the method of transforming it into mechanical wood pulp is
to-day a simple one. The blocks of wood are put into a barking
machine, a common form of which is provided with three knives upon
a rapidly revolving drum. The blocks of wood are brought in contact
with these knives, and it is essential that the bark is thoroughly cleared
away, otherwise the pulp will show dark spots. Knotty wood is also
objectionable, and as far as practicable, knots have to be removed, and
in many mills this is achieved by means of a revolving auger
or a spoon-shaped auger. The wood is cut into blocks by circular
saws, and it should be finally split in order that the inside of the wood
may be examined, as it is undesirable that any decayed timber shall
be made use of. Only sound wood should properly be used, as the
effect of rotten wood is sure to be detrimental to the pulp. The actual
process of grinding the wood is simple. Every kind of machine for
grinding consists of a grindstone (of sandstone), which runs at a very
rapid rate, and against the surface of which the wood is pressed, the
latter being kept constantly wet by a copious water supply. The wood
is fed into what are termed pockets, and placed so that its vascular
bundles lie parallel to the surface of the grindstone. The latter, in
revolving, tears from the wood individual vascular bundles, and occa-
sionally large splinters. The mass is carried by the water into a vat,
in which the revolving stone is placed, and from there to the sorting con-
trivances, by which various sized particles of wood are separated from
the other. In some modern grinders, the stone is fixed to a vertical
shaft, but most authorities consider a horizontal position preferable. If
time permitted, I wouM like to have described in detail the various
types of machine in use in various countries, of which the principal ones
are : Voelter's, Oser's, Voith's, Freitag's, Abadie's, and others. In this
connection it is highly essential that the water used shall be pure and

FOR PAPER-MAKING. !3

free from suspended solid bodies, sand or clay being particularly objec-
tionable, as they cling to the pulp, and affect it considerably when it gets
into the paper-maker's hands. It is, therefore, of course, highly neces-
sary that in establishing the site for a pulp-making centre, there shall be
a suitable water supply, otherwise the water used for grinding must
be carefully filtered, and in some mills where the water is not all that
could be desired, the water, after it had passed through the sorting
screens, is collected, filtered, and again used.

SORTING PULP,

which follows the grinding, is a very important detail. The sorter is,
in fact, a kind of sieve or series of sieves, and Voith's shaking sieve is
probably one of the best types in use. The frame rests on steel springs,
and the cranked axle, by an ingenious arrangement, secures uniform run-
ning, whilst the sieves jerk and shake rapidly, 400-500 motions per minute.
The application of springs reduces the wear and tear very materially,
and also minimises the noise. The particles of brown wood, having
thus been mechanically sorted, the pulp is conducted to the settling
vats, the dehydrating apparatus, or the board machines, as may be
desired. There are various processes for dealing with the particles of
wood which would not pass through the sieve, and, generally speaking,
it may be said that they are re-ground and again passed through a fine
meshed sieve.

The removal of water from pulp is a very important element, which
has to be taken into consideration, especially, where the question of
freight has to be considered ; and as a considerable quantity of pulp
has to be shipped over large distances, it is obvious that it is not desir-
able to carry more water in the pulp than circumstances necessitate.
Therefore, the importance of this is a matter which has a consider-
able bearing on the immediate advantage which accrues to a mill in
the position of making up its paper from pulp on the spot, but the full
consideration of this subject is a matter which is rather outside the
scope of this paper. There are many forms of drying apparatus, and
the preparation of perfectly dry pulp is now quite practicable. As
bearing upon the importance of selecting wood of the right class for the
particular purpose intended, I may here observe that Prof. Winkler
made interesting experiments with pulp from different varieties of wood,
which was exposed to the action of the air at a temperature of between

I4 USE OF WOOD PULP

30° to 50° F., and he obtained most interesting results, which are fully
set out on page 42 of Bersch's book.

To those of my audience who desire to go thoroughly into the
chemistry of paper-making, I can recommend a publication on this
subject by R. B. Griffin and A. D. Little, published by Howard, Lock-
wood & Co., New York. From memory, I believe the book I refer to
was published in 1894. It contains a mass of information of a very
useful character. Other valuable books to those who desire to go into
the matter of wood pulp thoroughly are: — " Vegetable Physiology"
(Goodale), also Schubert's " Die Cellulosefabrikation," and amongst our
British authorities, the writings of Mr. Clayton Beadle, Messrs. Cross
and Bevan, Dr. Stevens, and Mr. R. W. Sindall are amongst the most
instructive ; whilst the lectures delivered before this Society not very
long ago by my friend, Mr. Julius Hiibner, of the Manchester Techno-
logical School, also afford much information on the subject of paper-
making generally, and on the treatment of wood pulp from the paper-
maker's point of view.

CRUSHING.

Another interesting process in the preparation of mechanical wood
pulp was known as the crushing process, and the effect is the prepara-
tion of pulp from steamed wood without the necessity of grinding. This
has been known as the Rasch-Kirschner method. The steamed wood
was first converted into small pieces by means of a chopping machine
of special design, and then the wood was cut by a knife mechanically
driven lengthways into shavings of fixed size, or lengthways as well as
crossways. The small pieces of wood were then further reduced by
mechanical means, having first been subjected to the action of a stamp-
ing mill, and eventually were put into the Hollander, and I am told
that a very decent class of brown boards or stout wrapping papers
could be made in this way, and it is stated that boards and paper
especially suitable for roofing purposes made by this process had
special advantages. Some of such boards, impregnated with coal tar,
were said to be specially adapted for resisting the action of the weather,
and are described as " perfectly indifferent to water as well as to
changes of temperature." Attempts have been made to bleach the
pulp made from steamed wood, but so far as I cau learn the results
were not commercially successful.

FOR PAPER-MAKING. !^

Although it may possibly, strictly speaking, be somewhat beyond the
natural scope of a brief paper of this kind to go into the commercial
details of wood pulp making as regards cost, I have been favoured by a
gentleman who is in a special position to obtain information of this kind
with some very interesting figures. I am told that it requires 80 h.-p.
to make one short dry ton per day, or say, 90 h.-p. to make one long
dry ton per day, so that a mill developing 1,800 h.-p. on the turbines
should produce 20 tons of dry mechanical pulp per day, or say, 12,000
tons per year of 300 working days. Some Norwegian mills have very
small horse-power on the stones, but the latest and most modern mills
have at least 250 h.-p., whilst the Canadian mills are calculated on a
basis of 300 to 350 h.-p. per stone, and very large stones are used.
On the subject of the actual cost of producing mechanical pulp, I am
told that a pretty reliable estimate of the cost of the wood necessary to
make a ton of dry pulp is appoximately : —

Dry Pulp.

In East Norway ...... from 255. to 305.

In North Sweden „ 22s. to 255.

Canada : Lake St. John and portions of Nova

Scotia „ 135. 6d. to 155.

St. Maurice River and other districts „ 15*. to 225.

Wet Pulp.
The net cost, allowing for depreciation, is given approximately as follows : —

Per Ton.
Dry Weight.
£ s. d.

Modern mills in Norway, C/a . . . . .300

Modern mills in Sweden, C/a 2 15 o

Lake St. John i 17 6

St. Maurice District 2 10 0

On this subject, it should be borne in mind that the capitalisation
of a modern pulp mill is very high, and for a mill making, say, in
Scandinavia 6,000 tons wet, and 3,000 tons dry, f.o.b., value (roughly)
£10,800, the mill capitalisation would necessarily be from £20,000 to
£25,000 ; and hence it follows that to make 10 per cent, on the capital
a net profit on the produce of from 20 to 25 per cent, is necessary.

Small mills such as these form the majority in Scandinavia ; but
mills of this class could not be made to pay in Canada, where the biggest
mill (Chicoutimi) made 48,000 tons of short wet pulp in six months.
The entire capitalisation on this basis is 27 dols. per short ton dry per

j6 USE OF WOOD PULP

annum, or, say, £6 $s. per ton dry wet (2,240 Ibs. per year), making the
value of a short dry ton to be 13*50 dols. f.o.b. On this basis, a good
return will be shown, viz., a net profit of 20 per cent, on the article
yielding 10 per cent, for the purposes of dividend.

In the matter of the general cost of good bleaching pulp, of course,
local conditions here, as in the case of mechanical pulp, have a con-
siderable influence ; but I am told that good bleaching pulp may be
produced at a cost net (including everything, with the exception of
interest and depreciation) at about the following figures.

In Norway, at modern mills, about £6 per ton at the mill ; unbleach-
ing qualities would probably cost about 105-. per ton less. In Sweden
the cost varies considerably, but about £5 may be stated for " news "
pulp, and £5 los. for bleaching; and this is, I think, a low estimate
and can only be applied where the most favourable conditions are in
operation. So far, practically, no success has attended the Canadian
pulp mills in the manufacture of chemical pulp, and this I attribute
largely to lack of knowledge of the technicality of sulphite-making,
and through the lack of organisation as to timber supply. Mills have
been put down where timber could be had before building for 2*50 dols.
to 3 dols. per cord in limited quantities, but owing to lack of organisa-
tion and adequate security for the continuity of supply, prices have
been forced up in Canada to 5 and 6 and even 7 dols. per cord, which
is higher than in Scandinavia On the subject of capitalisation, a
modern mill would be doing well if capitalised so that every £5 of
capital produced one long dry ton per year ; but most mills are, I
think, capitalised on a great deal higher basis than this, and the fact
is, of course, obvious. This, however, is much better than mechanical
making, as 10 per cent, net on the article will nearly always give more
than enough for a 10 per cent, dividend.

THE USE OF WOOD IN PAPER-MAKING.

The first time, perhaps, that wood was used to any appreciable
extent in the manufacture of paper was when Koops published his
book, in 1800; but at that period it could not be made to compete
successfully against rags. The European wars had the effect of raising
the price of rags at the beginning of last century, so much so, that
there was a law which prohibited the burial of the dead in linen
shrouds.

FOR PAPER-MAKING. j7

Mechanical wood, or mechanical pulp, as we know it to-day, is, as
I have already said, produced by keeping short cut pieces of wood by
hydraulic pressure against the surface of a rapidly revolving stone,
and was the first form in which wood was used in any considerable
quantity.

^Mechanical wood has very little felting power, and is only capable
of producing a weak paper, which contains practically all the ingre-
dients of the original wood, and from the time of (its discovery up to
the present it has only been used for lower class papers. It, however,
constitutes the great bulk by weight of our paper -making materials, as
a common newspaper contains upwards of four-fifths of this substance, ;

CHEMICAL PULP.

A great change took place in the manufacture of paper on the
development of the sulphite process. This process consists in treating
chips of wood under a pressure of about seven atmospheres with a
solution of bi-sulphite of lime or magnesia for a period of from eight
hours to three days The first patent was undoubtedly taken out by
Benjamin G. Tilghman, of Philadelphia, in 1867. His original speci-
fication practically covers the various methods employed by subsequent
inventors. He started by boiling in lead-lined cylinders. Although
an excellent fibre was obtained the engineering difficulties rendered it
necessary to abandon his original process.

The preparation of wood for the chemical process is somewhat
similar to that employed in preparing the wood for grinding. The
wood is brought from the river or from the stacks in the mill yard,
sawn into suitable lengths, past through the barking machine, then
through the knotting machine, afterwards fed into the chipping
machine, which, at a great rate, reduces the wood into small chips. It
is then screened, and any further knots which appear are removed,
and then the wood is taken along by a conveyer from the screens to
the top of the digester house, and fed into the digesters through the
manhole at the top. I have seen, at the modern Chemical Pulp Mills,
in Sweden, Norway, Finland, United States, and Canada, digesters
with a capacity of 15 tons dry pump, and I have heard of a mill in
North Sweden with a digester which will carry at one cooking 20 tons
of dry pulp.

B

1 8 USE OF WOOD PULP

THE PIONEERS OF CHEMICAL PULP.

The actual date of the invention of wood pulp is more or less prob-
lematical, as the evolution of wood pulp has undoubtedly extended
over a very considerable period, but the reference to Tilghinan may be
accepted as established. Some years ago a very interesting corre-
spondence appeared in Papier Zeitung, and Professor F. Fittica
asserted that (a) Mitscherlich was entitled to the honour of being
recognised as the inventor of sulphite. The editor of Papier 2eitung
apparently did not wish to share the responsibility for that statement,
and I think the editor of our esteemed German contemporary was well
advised in the view he took, and in the course of a very intelligent
correspondence, various more or less authoritative people put forward
the names of Ekman, Tilghman, Rismuller, and others, and various
information wras forthcoming regarding priority, but the consensus of
opinion seemed to controvert Professor Fittica's original argument, and
Wochenblatt mentioned C. D. Ekman as the father of the sulphite
industry. About the year 1872 a well-known publication, in discussing
this particular matter, argued that it was due to Ekman that the
manufacture of Mitscherlich's cellulose on a large scale was rendered
chemically possible, Prof. Fittica, however, who stuck to his guns in
championing Mitscherlich, said that Ekman did not operate with
calcium sulphite according to Mitscherlich's process, but he used mag-
nesium sulphite, a salt that was without value owing to its inconstancy,
and, consequently, was of no technical consequence as compared with
calcium sulphite, but subsequently Ekman undoubtedly made a success
of the magnesium sulphite process. However, his method was kept
secret so that even for that reason the same could not have been, in
Fittica's opinion, used by Mitscherlich. In this connection it is worth
while remembering that originally Ekman's mill was in operation from
1874 to 1897, but was, of course, re-opened later. Fittica further
stated that Tilghman was ahead of Mitscherlich, in so far as he used
diluted sulphurous acid for transforming wood into cellulose, and it is
significant that in the year 1886 Tilghman, in his patent, No. 2924,
mentions that " that an addition of bi-sulphite of calcium to sulphurous
acid is advantageous." However, it subsequently appeared that he
had not used the salt alone, nor did he use the comparatively low
temperature recommended by Mitscherlich. Moreover, he was unable
to surmount the technical difficulties combined with these state4

FOR PAPER-MAKING. jg

processes, and subsequently discontinued his experiments in the year
1867, after struggling for two years, and losing 20,000 dols. or over. In
the year 1882, Ritter and Kellner took out a patent, and at this time
Mitscherlich's factory in Munden was flourishing, having been started
in 1875, and having made considerable progress, and the friends of
Mitscherlich claim that the early manufacturers, in a general and theo-
retical way, operated on the Mitscherlich principles, their process
differing only in insignificant arrangements. Prof. Kirschner states in
his work, " Zellstoff," that F. A. Rismuller was the first to produce
practically valuable cellulose on a considerable scale, under Mitscherlich's
direction, in his factory. The names of O. Vogel, in Zell, is also
alluded to by Prof. Kirschner, but there is no evidence that Vogel played
any great part in the actual invention, although there is evidence that
at one time he was assistant to Mitscherlich, and subsequently Vogel
put down his own plant, which was arranged according to the Mits-
cherlich process. In 1884, in favour of Tilghman, Mitscherlich's patent
No. 4179, wras suspended by the German Court, and history would
support Tilghman's contention. Some reliable authorities point out that
sulphurous acid and its preparations had formerly been used only for
bleaching cellulose wood pulp, and as late as 1867, after the issue of
the Tilghman patent, Mr. Krieg — whose opinion is worth something —
emphasised the fact " that wood pulp was not suitable for fine papers."
Heldt states that in 1869 sulphurous acid should not only be called
bleaching material, but bad bleaching material, because it imparts a
yellow colour. At about that time, apparently new methods were
discovered to change the wood into cellulose by the use of alkalies, and
it is recorded that in 1872 considerable progress was made in this direc-
tion. A year later, in 1873, Menzies published a new process, accord-
ing to which wood was treated in the damp state with chlorine, and
in that same year Aussedat seems to have paid considerable attention
to bringing wood and chlorine together in steam pressure. Blyth and
Suthby made combinations of both the first and last mentioned methods
by first submitting the wood to the action of alkalies, and subsequently
to high steam pressure, and this method was amplified and improved
by lingerer. Then Mitscherlich came into the market with a new
arrangement to use bi-sulphite of calcium, and demonstrated that by a
solution of calcium sulphite with strong acids, he prepared a solution of
calcium di-sulphite. Following this success, and assisted by the use of

20 USE OF WOOD PULP

Swedish Patent No. 2939, he succeeded during that year in the
performance of technical trials on a large scale, and in 1875 he obtained
a directly prepared solution of di-sulphite, such as he had previously
obtained from calcium carbonate. At that time he obtained the action
of pure calcium bi-sulphite on wood, preparing the salt by running
sulphurous gas over pieces of carbonate of calcium. Afterwards he
constructed a tower for making the bi-sulphite of calcium. This method
seems to have been considerably followed, and in 1866 a sulphite mill
was built in America on Mitscherlich's lines and according to a report
from Thilmany (1894), the Mitscherlich process had been favourably
adopted, and to such an extent that about that time there were forty
boilers in operation in the United States and four in Canada ; and the
total yearly product in the States at that time was about 50,000 tons.
On turning to Muspratt's technical handbook of that time, Mitscherlich
is mentioned as the inventor of sulphite cellulose. Without committing
himself to Stohmann, whose opinion has been freely quoted, it is signi-
ficant that this authority mentions Tilghman and others, but merely to
show that their experiments, as compared with Mitscherlich's success,
had no weight, since they were not performed in a practical manner,
and because they gained no technical success.

Stohmann, however, was subsequently reminded that the earliest
edition of Muspratt contained no mention of Mitscherlich, although his
mill in Munden was then in secret operation. Prof. Fittica, on this
subject, summarises his opinion in these words : " Tilghman used the
sulphurous acid, or he intended to use the same ; but he did not use
the sour calcium salt of the acid, and did not prepare or use the same in
its pure state, in which condition only is it practicable for that purpose.
For this reason, Tilghman had to discontinue, after ten years of restless
activity." Ekman's magnesium sulphite, however, undoubtedly and
finally proved to be a suitable preparation. Several other experimenters
also failed to comprehend the action of the temperature, so that also in
this respect we must give Mitscherlich the credit due to him. As
might have been expected, Prof. Fittica's contentions provoked very
considerable criticism, and some rather severe comments, and returning
to the fray, Fittica says in 1904: In my history, in the manufaturing
of sulphite stuff, I mentioned especially that it was Tilghman, besides
others, who had already undertaken to make experiments to make
sulphite fibre by means of sulphurous acids, but that it was Mitscherlich

FOR PAPER-MAKINC. 2t

who provided a practical foundation to these experiments, and he must
be called the first inventor in case the question arises as to a really
practical invention. The germs of the idea of a new invention, a new
principle, a new law, a new conception of the universe only take root
gradually. Each idea has its forerunner, and these forerunners are
present in every direction. . . . The person, however, who forms
these ideas in the practical shape must be considered the inventor,
because his forerunners have not performed a technical realisation. . . .
" Consequently," adds Prof. Fittica, " I repeat that it was Tilghman,
besides others, who furnished the idea of manufacturing sulphite fibre,
but it was Mitscherlich who added hand and foot to the practice, and,
therefore, must be called the real technical inventor of the sulphite
cellulose fabrication." Quite recently, Prof. E. Kirschner added a very
important contribution to this controversy, and wrote that Ekman, in
Bergvik, Sweden, produced regularly large quantities of the valued
sulphite pulp in 1874. That was long before Mitscherlich, and Prof.
Kirschner adds that Fittica did not apparently seem to be aware that
magnesium bi-sulphite, and also sodium and potassium compounds,
produced not only the same effects in the sulphite process as calcium
bi-sulphite, but would be even preferable to the latter, were it not for
the higher cost of the bases contained in the former. Prof. Kirschner
went at some length to substantiate his arguments by giving interesting
chemical details, and went on to observe that " seeing that Ekman, in
Bergvik, had not only magnesite, but also lime close at hand, and the
latter could be bought at a lower price, we are justified in concluding
that Ekman was well aware of the technical conditions offered by a
magnesium bi-sulphite liquor in contrast to one prepared from lime.
From 1875 and onwards, Ekman pulp was to be found in European
markets. Later on in 1878-1880, the Ekman pulp was certainly of a
higher quality and fetched a higher price than the impure irregular
material from Hann-munden, where the Mitscherlich process was being
worked." Kirschner further controverted the suggestion that the poor
qualities attributed to Ekman pulp by Fittica were not justifiable, and
he argued that Mitscherlich was largely a copyist of Rismuller and
Vogel. To those who are sufficiently interested in the subject, a perusal
of Ekman's and Francke's patent specifications for the manufacture of
sulphite pulp will probably be of considerable historical interest, and I
am indebted to Mr, Clayton Beadle for a perusal of the same. This

22 USE OF WOOD PULP

patent seems rather to bear out the contention that at a certain period
quite a number of distinguished men were struggling to place what we
now term chemical pulp on a commercial basis, and that Ekman
contributed considerably to the solution of the difficulty.

C. D. Ekman (a persevering Swedish chemist), who died last year at
Gravesend, therefore appears, in my judgment, to have been the first
to make a commercial success of the sulphite process. He set to work
in 1872, using a solution of bi-sulphite of magnesia. His process was
worked secretly until about 1879, when it was introduced into the Ilford
Mills, near London ; after which, in 1884, the proprietors of the patent
erected large mills at Northfleet, where the process was conducted by
the Ekman Pulp and Paper Company, and was finally abandoned in
this country in 1903-04, it being no longer possible to compete with
foreign countries, on account of the cost of timber.

The great difficulty in the way of making the sulphite process a
success was due to the corrosive action of the sulphite liquor. This
liquor quickly eats through iron, and has a certain amount of action
upon lead. Lead linings were at first used at Northfleet, but owing to
the difficulty of " creeping," lead had to be abandoned. The " creep-
ing " is due to the difference in the expansion of the lead and the outer
lining, causing the lead to " packer." I am informed that the first
lining came away completely, like a jelly out of a mould. Many linings
were substituted, among them cement. The difficulty was finally over-
come by introducing a brick lining.

Wood pulp for paper- making was manufactured at Guardbridge, in
Scotland, very many years ago on the site of the Guardbridge Paper
Company's mills. It was also made at Bruce's, at Kinleth Paper Mills.
The Messrs. Tait have made wood pulp at their paper mills at Inverurie
for over twenty years past. Then a plant was erected at Inverkeithing.

In England, Ekman made pulp at Ilford. Mr. Edward Partington,
one of the most experienced authorities on wood pulp in this country —
who would have been with us to-night but for the fact that he is leaving
for the Continent — made pulp for years at Glossop. The Kellner-Part-
ington Paper Pulp Company also made pulp at their mills at Barrow-
in-Furness.

Mr. (now Sir John) McDougall, ex*Chairman of the County Council,
made wood pulp at Millwall.

Then there was another company at Goole — which made pulp in

k)R PAPER-MAKING. 23

1890, but is now discontinued — and the West Hartlepool Company,
which also made wood pulp. Some seventeen or eighteen years ago, I
remember being invited to the mills of the East Lancashire Paper
Company, where in a small building I saw wood pulp being made by
what was then known as the Graham process.

A Scotch friend tells me that the Guardbridge Soda Pulp Mill was
erected in 1870-71, and it worked for about two years or so. The
boilers were of Mr. Sinclair's patent vertical, having conical ends, the
fire being underneath, having spiral flue so that the gases ascended and
passed through an iron-funnel chimney on the top. To prevent the
burning of the wood, there was provided a perforated cage having ij
inch space between said cage and outer shell for the liquor. There was
a down-take pipe about 5 inches diameter to take down the liquor
through the centre of the cage. This down-take pipe was removable, so
that it could be taken out when the boiler was being filled. These boilers
were 10 or 12 feet deep, and about 4 feet diameter, the working
pressure being about 2oolb per square inch. Caustic soda was used,
and the wood was boiled off in three hours.

The Goole Company commenced making pulp in 1890, but has
not been in operation for some time, The North Eastern Pulp
Company also turned out pulp, but is not now doing so.

Messrs. Brown, Stewart & Co. had digesters at Newton Paper
Mills and at Dalmarnock Mills for making their wood pulp ; but this
also has all been discarded. This was about twenty years ago.

In those days the cost by Francke's process of wood and chemical
plant for the production of 30 tons of sulphite pulp per week was esti-
mated at £8,000, and with the Ekman process — then just at work at
Ilford — £13,000 to £14,000 was spent on plant, machinery, and wood
to produce 20 tons per week. The cost of raw wood to make a ton of
paper at Hull or Liverpool was estimated at £5.

In the early days of sulphite pulp manufacture I went to Sweden
and studied the bi-sulphide process at Francke's mills. Mr. Edward
Partington and Mr. James Galloway about this time visiting the same
mills, with the view of adopting the process. Subsequently Mr.
Partington erected a sulphite wood pulp plant at Glossop, and worked
a system of his own. In 1844 Keller took out letters patent in Germany
for a wood-pulp grinding machine, but for want of capital sold it to
Voelter. J. Macfarlane, of the Canada Paper Company, told me that he

^4 USE OF WOOD PULP

first introduced wood to the country in 1874, that he offered some bass-
wood to Bruce's of Kinleith — and was laughed at, He finally offered
them a farthing per pound over and above the market price for the
paper ; the pulp was eventually accepted, and proved such a success
that the Bruces, very naturaly, kept the matter to themselves as long
as possible.

The Partington process acquired by the American Sulphite Pulp
Company about 1884 was the first to be made use of in the United
States of America. It was also conducted in this country by the Kellner-
Partington Paper Company, but was, I believe, abandoned a few years
ago.

Mitscherlich, who by the way, was Professor of Chemistry of Munich,
began his experiments with the sulphite process about 1876, and later
on went to Thodes Mill, near Dresden, and has already been referred to.
He started commercially about 1881.

Many lawsuits were fought in respect of the rival patents, which
showed very close resemblance in their claims, Behrend, in 1883,
disputed the validity of the Mitscherlich patents on the grounds of the
priority of Tilghman British patents, and the German Board of Patents
concluded that the Mitscherlich process did not differ from that of
Tilghman's to entitle it to protection. There were numerous patents in
connection with the lining and the digester which we need not refer to
in detail.

The treatment by the sulphite process consists first of all in prepar-
ing the liquor. This is done by causing the vapour of sulphurous acid
obtained by burning either " pyrites " (sulphide of iron) or sulphur in
ovens, and conveying the vapour up from the bottom to the top of a
tower of about 105 feet in height, packed with limestone — a spray of
water is introduced at the top and trickles through the limestone. The
vapour combines with the water to form sulphurous acid, which acts
upon and dissolves the limestone, forming bi-sulphite of lime. In the
Ekman process, a stone consisting chiefly of magnesia is used, whereby
bi-sulphite of magnesia is produced. The liquor, standing at about 11°
Tw., and containing about two-thirds of the sulphurous acid in the free
state and one-third in combination with lime, is run into a sulphite
digester, which is closely packed with chips of the wood until the liquor
just covers over the wood. The lid is put on, steam is introduced until
the temperature slowly rises to about ioo°C. This causes all the air

FOR PAPER-MAKING. j>$

from the pores of the wood to escape and the solution to take its place,
and takes a few hours. The temperature is then increased by the
introduction of further steam until it slowly rises to, say, i I7°C. ; 1 15° is
about the temperature at which chemical action begins to take place ;
120° is the maximum temperature above which it is unsafe to go. The
temperature therefore must be maintained within these limits during
the process of boiling. The progress is judged by withdrawing samples
of the liquor and examining their colour, sedimentation, and by other
means. When the process is complete, the digester is blown off, the
pulp washed with hot water, after which it is put into potchers, where
it is further washed, and then it is passed through screens for separating
out any untreated particles, and collected in the machine in the form of
sheets containing 50 per cent, moisture, packed into bales for shipment.

If required in the bleached state, when in the potcher, it is mixed
with solution of bleaching powder from 10-20 per cent, of the weight of
the material, emptied into " steeping " tanks. When the chlorine is
exhausted, the liquor is allowed to drain away, and the bleached product
restored to the potchers and treated in the same way as the unbleached
product.

'Chemical wood pulps now enter into the manufacture of the highest
class papers, and such a degree of excellence has been achieved in this
that only an expert could tell the difference between a chemical wood
fibre paper and an expensive all rag paper.

SODA PROCESS.

The heating is effected either by means of coils or live steam. When
the latter, allowance must be made for the amount of condensation.
Little makes the statement that the temperature can be raised quickly.
I have, however, reason to know that with soft soda aspen the tempera-
ture has to be raised slowly and with the utmost care, and also lowered
again. The filling of the boiler is similar to that of the sulphite ; the
full pressure is, however, reached as quickly as possible, and maintained
until the end of the treatment, the pressure formerly adopted being from
60 to 75 Ibs. per square inch, but latterly it was employed at about 100 Ibs.
per square inch, and sometimes no. The time of boiling is from eight
to ten hours : as the pressure is increased the strength of the liquor can
be somewhat diminished. Unlike the sulphite pulp that obtained by
means of the soda process is of a greyish brown colour, whilst the liquor

26 USE OF WOOD PULP

is a darkish brown and of a peculiar odour. This liquor contains the
incrusting and resinous matters in combination with the soda as a soluble
soap.

Caustic soda, being an expensive chemical, has to be recovered.
This is effected by evaporating the liquor down to a thick syrup, after
which they are made to flow into a revolving furnace, where they catch
on fire, their own organic matters supplying a large amount of heat
necessary for the incineration as well as for the evaporation of the
weaker liquors. The evaporation is much economised by the adoption
of what is known as the triple or quadruple effect evaporator, by means
of which the water is removed at the least possible expenditure for fuel.
The incinerated ashes as discharged from the furnace appear in greyish
and blackish masses in the form of a sort of clinker. This mass,
consisting of carbonate of soda mixed with carbon, is " lixiviated " or
treated in hot water, whereby the soluble carbonate of soda goes into
solution, leaving a black mud of charred and useless matter, from which
the liquor is freed by sand filtration. The clear liquor standing at
from i6-2O°Tw. is heated in iron coppers, and causticised by treatment
with caustic lime, whereby the carbonate of soda is converted into
caustic soda, and the caustic lime into carbonate of lime or chalk. The
chalk forms a sludge at the bottom of the vessel, from which the
remainder of the liquor can be removed by filter pressing.

The sludge is pumped into a filter press to remove the liquor still
remaining, and water caused to percolate through to remove the last
traces, A clear caustic liquor is ready to be used again in the process
of boiling. The process of recovery results in a certain amount of loss
of the soda, amounting to about 15 per cent. This has to be made
good by the addition of a certain amount of caustic or carbonate of
soda. Soda wood pulp is generally of stuff of the nature of sulphite,
and though of darker colour, is, as a rule, easier to bleach. Of recent
years the soda process has gone to a large extent out of use and has
been replaced by the sulphate process. This process consists in treat-
ing wood chips in an iron digester with sulphate of soda containing
in the first instance a certain amount of caustic. The process is
conducted very much like the soda process. It is carried up to the
stage of the recovery process in a similar manner ; in the soda process,
however, the recovered ash consists of carbonate of soda, whereas in the
sulphate process the recovered ash consists of sodium sulphide and

PAPER-MAKING. 27

sulphate of soda. The liquor ready for using again consists of caustic
carbonate, sulphide, and sulphate of soda. The process is cheaper
than the soda process, because instead of making up for the loss of the
soda by the addition of caustic or carbonate, it is made up with
sulphate of soda, which is a much cheaper chemical ; sulphate passing
through the recovery process is reduced by the organic matter to
sulphide ; a considerable amount of this sulphide is decomposed through
the treatment of the wood, giving rise to sulphuretted hydrogen. The
gases emanating from a sulphate factory render it necessary to conduct
the process in districts where noxious factories are not interfered with.

A great deal of the wood pulp sold as soda pulp is, I am assured
by a leading expert, in reality sulphate, and he tells me the proportion
appears to be increasing every year. On this subject I am unable to
express an opinion, but I am quite certain the British paper-maker
secures delivery of chemical pulp capable of being used for the purpose
intended.

POSSIBILITIES OF WOOD PRODUCTS.

Prof. E. Pfuhl has recently published a very interesting book on
" Paper Yarn : Its Production, Properties, and Uses." In this book,
Prof. Pfuhl gives an account of the progress that has been made in
producing yarn from threads prepared by a wet felting of fibres, and
the results are most interesting. The raw material, consisting largely
of chemical wood pulp, is dealt with in a special manner in the beating
engine, so as to reduce the length of the fibres to the necessary extent,
and convert the whole into a good felting paper pulp, The pulp is
then brought on to a Fourdrinier machine, and a layer of this pulp
produced in the ordinary manner, after which it is divided into a
number of narrow bands, which bands are twisted by mechanical means,
and converted into threads. According to Prof. Pfuhl there are two
processes in practical working. One is for the production of a material
known as " xyloline " based on the patents of Claviez & Co. In this
the strips of pulp, as they come away from the machine, are wound on
to reels, and these reels are then fixed to revolving forks, so that on
winding the strip off the reel, it receives the necessary twist, and is
mechanically treated otherwise. The material produced yields a strong
yarn, and is so cheap that a complete suit of clothes can be sold for
js. to los. It is further stated that it can be washed without being

OF WOODFULF*

damaged in any way. Silvaline is also produced at Golzern-Grimma
on the lines invented by Herr R. Kron. Here paper is divided into
strips and subsequently spun into threads, and the machinery is very
delicate and beautiful. The first factory was erected in Spain, near
Bilbao, and another factory has been erected in Holland. Other
factories at Rattimau and Mesterlitz, in Germany, are being erected,
and the enterprise is extending to Russia, \and there is no doubt that
silvaline and xyloline will enter into direct competition with jute, and
possibly coarse cotton yarn. )

The rapidity of the progress made in this branch of technology is a
marvel among modern enterprises, and it is doubtful if, in the history
of the nations of the world, any one industry has achieved such a
success in comparatively so short a period of time. Probably few
realise what an amount of wood pulp the publication of our daily
newspapers requires. I may here remark that one London " daily "
has recently entered into a contract for the purchase of 10,000 tons of
paper per annum for three years, and I think it would be fair to
estimate that each day one of our large London daily papers consumes
to acres of an average forest./ Wood pulp owes its wide range of
application to the fact that itvis a material that can be made to any
degree of consistency, from a delicate almost intangible fabric to a
dense mass as hard as metal. It can be dyed to any colour or shade ;
it can be rendered fire and waterproof ; and in the hands of the chemist
may be converted into a number of very useful combinations.

Ekman, it is not generally known, succeeded in producing a
substance which he called " Dextrone," from sulphite liquors. This
substance had special qualities. It could be mixed with glue and
precipitated in the form of leather when diluted with water only. It
could be used in giving strength to brown papers, in weighting jute, or
as a mordant for dyes. It was of the nature of tannin, and yet it had
quite distinct properties. Seeing that for every ton of chemical wood
pulp produced about a ton of dextrone would be recovered from the
liquors, an enormous quantity could be produced if required. This
substance was not, I think, manufactured in England after the Ekman
works stopped making pulp. Captain Partington has recently made use
of sulphite liquors for watering the roads, and claims to get very
excellent results.

Wood pulp is now used for the manufacture of nitro-celluloses.

FOR PAPER-MAKING. 2y

For explosives the pulp has to be of a special nature. It is also used
under the name of " Cellulose Wadding/' prepared under Feirabend's
Patent No. 3061, where it replaced cotton wool for surgical bandages,
giving most excellent results. It is also, as Pfuhl reminds us, coming
into use in the form of paper in narrow strips, which are afterwards
spun into filaments and woven into garments, such as under Kellner-
Turq processes and the Silvaline Yarn process. Then, of course, [it is
used in considerable quantities now for manufacture of artificial silk. )
According to the Stern process, it is converted into viscose by Cross,
Bevan and Beadle's process, and then spun into fine portions through
a special solution from which it emerges in the form of filaments. For
this product the inventors — all three British by the way — were awarded
the Grand Prix at the last Paris Exhibition. They have also received
numerous other valuable awards.

In America, where they have no esparto, the printing papers for
process blocks can be produced by the aid of aspen, which fibre under
the soda process makes a good substitute for esparto. I think,
perhaps, not sufficient attention has been paid to the subject of the
great differences in the qualities of papers made from wood pulp
according to the kind of pulp used and the process adopted. Thus,
on the one hand, we were able to produce soft and spongy papers,
excellent for filter papers, and, on the other hand, imitation parchments
from Mitscherlich pulp, close, transparent, grease-proof, the latter being
produced by the aid of the basalt lava beater roll.

Then we have the milk of lime process, whereby bi-sulphite liquor is
now produced by passing the fumes of sulphur through milk of lime
instead of by allowing it to pass up towers filled with limestone, which
is the general system in use in Sweden and Norway. The liquor made
by the milk of lime process is identical with that of the ordinary
method, but it has the great advantage that it produces a solution of
absolute uniformity in strength, a difficult thing with the limestone, but
a very important thing for ensuring regularity in the cook.

DIGESTER LININGS.

One of the most important things in the history of wood pulp has
been the question of digester linings. The Mitscherlich lining in 1894
consisted of tarred pitch to protect the shell, then a layer of thin sheet
lead, and on top of this two courses of specially acidresisting bricks,

30 USE OF WOOD PULP

formed with tongue and groove, cement being used sometimes with the
bricks. Some foreign mills place the lining of lead between the two
courses of bricks. In a digester heated by indirect heat, a coating of
the sulphite of lime can be produced on the surface, which gives a
protection for the metal. Jung and Lindig used the coating of double
silicate of lime and iron. Kellner took out numerous patents for
cements, consisting either of ground slate and silicate of soda, or
powdered slate and glass and Portland cement, One of the earliest,
and one of the most successful, linings was prepared by Wenzel,
consisting of a special cement, for the most part a manufacture of
Portland cement and silicate of soda, set in blocks in wooden moulds
made to conform to the shape of the digester. Finally, excellent
results were obtained by the use of Portland cement alone, which in
many cases is reinforced by a facing of special brick or tile, the usual
thickness of the cement lining being 4 in. All cement linings are more
or less porous when applied, but in use soon fill up with sulphate and
sulphite of lime. After numerous years of work, a great many
failures, a great many patents, lawsuits, and infringements, a brick has
been introduced for lining which answers the purpose. Until a suitable
lining could be devised, the sulphite process could not be regarded as a
success. As the early troubles writh the linings made it impossible to
make pulp cheaply, and the corrosion of the shell contaminated and
discoloured the pulp, most of the pulp on the market now as soda pulp
is in reality made under the sulphate process, which consists of a liquor
containing sodium sulphate, sulphite, carbonate, caustic, which before
burning to ash is fortified by the addition of sulphate of soda, the sul-
phate being reduced to sulphite during the process of recovery. This
process is cheap, but the nauseating gases evolved during the process
at one time made it a difficult matter, except in out-of-the-wray
districts.

METHODS IN THE MILL REVOLUTIONISED.

I think I might point out that the introduction of wood pulp has had
a considerable effect upon the way that mills are constructed nowadays
in this country. Before the introduction of wood the raw materials
were treated from beginning to end in the mill ; now a mill buys wood
pulp, which is put direct into the beaters, all the preliminary processes
being obviated (except if bleached) .

FOR PAPER-MAKING. 3!

As to the permanency of wood papers, there is still difference of
opinion. Mr. Clayton Beadle tells me he would not like to recommend
even the very best bleached wood in paper required to be of an abso-
lutely lasting character, but would give the preference to mixtures of
cotton and linen. But it should be remembered that every year sees
improvements in the treatment of wood, resulting in a more lasting and
durable fibre. In course of time we may be compelled to alter our
views.

The complete statistics bearing on the subject are much too lengthy
and complicated to attempt to read in the limited time at my disposal.
They will be found in the Appendix. I may, however, trouble you with
one or two figures : —

In 1903, we imported into Great Britain 211,823 tons of chemical
dry pulp, of the stated value of £1,842,082. This came chiefly from
Sweden and Norway, and only 1,356 tons were sent to us from British
possessions. Of chemical wet pulp we introduced, in 1903, 21,279 tons
almost entirely from Sweden and Norway, and value was £82,012.
In the same year we imported mechanical dry, 8,268 tons, of the value
°f £3°)192 I and of mechanical wet, we imported^ in 1903, 336,788
tons, of the value of £752,297,

It is worth noting that Canada supplies us with a by no means
insignificant portion of the mechanical wet pulp.

In 1901, Canada sent us 48,551 tons, and in 1903, Canada supplied
us with 71,664 tons of the value of £157,918. In this class of pulp,
Sweden, in 1903, sent the pulp of the value of, roughly, £101,000; but
Norway received £490,949 for the mechanical wet wood pulp sent to
us for that year.

According to official figures, British paper makers paid : — In 1903—
£1,642,082 for chemical dry pulp ; £82,012 for chemical wet ; £30,192
for chemical dry, and £752,397 for mechanical wet, being a total of
£2,506,583.

I should be very sorry indeed to trespass on any contentious ground
or to encroach on political subjects, but without taking any side in the
matter I may say that in connection with the fiscal controversy, in the
event of a duty being put upon manufactured articles coming into this
country, it may be somewhat difficult to classify certain kinds of wood
pulp in this connection. It is a rather debateable point as to whether
certain classes of wood pulp are manufactured articles or not, or tg

32 USE OF WOOD PULP

what extent it may be termed " raw material." I believe Mr. Cham-
berlain is credited with having been good enough to look upon wood
pulp as raw material, but I do not think that this is exactly a subject
which is likely to cause paper-makers or pulp producers many sleepless
nights in the immediate future, although the time may come when the
questions will have to be considered from the point of view to which I
have alluded.

APPENDIX I.— PATENTS.

As will be understood, a very large number of patents have been
taken out by those concerned in the development of wood pulp making,
and in importance relating to the same. The following may be taken as
covering some of the most important patents from 1867, when Tilghman
was granted the initial patent : —

Archbold, George. 1883 ; manufacture of paper pulp.

; manufacture of paper pulp.

Biron, Jean B. 1867 ; disintegrating wood to form pulp, etc.
Ekman, Carl D. 1882 ; treating wood.

— ; method of treating wood.

; treating fibrous vegetable susbstances to obtain fibre

suitable for paper making.

Francke, David Otto. 1884; manufacture of paper pulp.
Graham, James Anthony. 1883 ; treating fibrous substances.
Haskell, J. R. 1867 > treating and separating vegetable fibres. [Not on

sulphite process, but his claim covers first steaming the fibres and then

condensing steam by shower of cold liquor so as to force liquor into the

wood, as in later patents of Mitscherlich.]
Kellner, Charles. 1886; method of sizing paper to prevent the sulphite and

ground pulp from turning yellow. [He precipitates the rosin size with a

sulphite salt]

Minthorn Daniel. 1885 ; treating vegetable fibre.
Mitscherlich, Alex. 1886; boiling fibres with sulphite.
• 1886; paper pulp (process for manufacturing).

— — — — 1889 ; manufacturing thread from short fibre.
Pictet, R. P. 1885 ; manufacture of pulp from wood matter.
Pond, Goldsburg H. 1886 ; manufacture of paper pulp from wood.

— — — 1886 ; machine for manufacture of wood pulp.

— • 1886; manufacture of wood pulp.

Ritter, Eugen Baron, and Carl Kellner. 1885; apparatus and manufacture

of cellulose from wood.

1885; progress of manufacturing

cellulose.

FOR PAPER-MAKING.

33

Ritter, Eugen Baron, and Carl Kellner. 1886 ; progress for manufacturing

sulphites.

Tilghman, B. C. 1867 ; treating vegetable substances for making paper pulp.
1869; progress of treating vegetable substances to obtain

fibre.
Wheelwright, Charles S., and George E. Marshall. 1884; apparatus for

treating wood.

II. — THE PULP IMPORTED INTO GREAT BRITAIN DURING THE MONTH
OF APRIL 1905, WAS:—

Quantities.

Month ended soth April.

Four months ended soth April.

1903.

1904.

1905.

1903.

1904.

1905.

Tons.
2,168
60,538

Mechanical :—
Dry ....
Wet ....

Tons.

473
26,666

Tons.
228
I9.I45

Tons.
628
15.770

Tons.
2,284
8i,953

Tons.

2,548
86,597

Total .

Chemical : —
Dry ....
Wet ....

Total .
Total of Pulp of Wood .

27,139

19.373

16,398

84,237

89,U5

62,706

14,226
3,745

n,478
1.859

13,650
985

51,983
7,949

46,215
8,049

53,149
6,260

I7,97i

13,337

14,635

59,532

54,264

59,409

45.no

32,710

31,033

144,169

143409

122,115

Value.

Month ended soth April.

Four months ended soth April.

1903.

1904.

1905.

1903.

1904.

1905.

Mechanical : —
Dry ....
Wet ....

Total .

Chemical :—
Dry .
Wet ....

Total .

Total declared value of
Wood Pulp .

2,348
60,515

£
1,047

42,412

£
3,141
36,244

£

12,273

191.135

£

12,443
189,874

11,058
140,230

62,863

43,459

39,385

203,408

202,317

151,288

111,340

i3,76i

90,587
7,278

115,076
3,193

411,132
30,607

362,507
30,800

443,869
25,353

125,101

97,865

118,269

441,739

393,307

469,222

187,964

141,324

157,654

645,147

595,624

620,510

34

USE OF WOOD PULP FOR PAPER-MAKING.

III.— GREAT BRITAIN.

Imports of Wood Pulp compiled from the
Statement of Trade : Years 1901,

Blue Book of Annual
1902,1903.

Quantities.

Value.

1901.

1902.

1903.

1901.

1902.

1903.

Chemical, Dry.
From Russia
„ Sweden
„ Norway
„ Germany
„ Holland
„ Portugal
„ United States of America
„ Other Foreign Countries

Tons.

84,955
52,161

2,324
3,535
1,635
7,500
2,984

Tons.
2,404
102,174
57,413
3,8,70
5,309
i,576
2,878
695

Tons.
3,907
127,510
62,446
5,362
4,669
1,884
3,785
904

£

746,237
457,074
21,950

35,00°
13,908
63,491
25,640

£

18,443
824,825
466,213
32,665
46,776
12,984
23,848
5,991

£

29,906
971,665
490,354
45,843
40,615
I4,52i
31,254
7,179

Total from Foreign Countries .

155,094

176,319

210,467

1,363,300

1,431,345

i,63i,337

From British Possessions

18,707

9,124

i,356

154,742

76,210

io,745

TOTAL .

173,801

185,443

211,823

1,518,042

1,507,555

1,642,082

Chemical, Wet.
From Sweden . •
„ Norway . . p .
„ Other Foreign Countries

5,638
8,383
35i

4,587
8,358
216

4,908

i6,339
32

36,986
42,371
3,i5i

20,994
42,281
1,929

19,908
62,846
153

Total from Foreign Countries .

14,372

13,161

21,279

82,508

65,204

82,012

From Canada . •

774

—

—

5,322

—

—

TOTAL
Mechanical Dry

15,146

13,161

21,279

87,830

65,204

82,012

From Sweden
„ Norway
„ Germany .
., Holland
'„ United States of America
„ Other Foreign Countries

4,122

2,464

75
710

3,789
62

3,957
2,394

858
1,727

100

3,067
2,278
36

245
160
464

31,500
16,784

421

5,605
27,667

337

23,861
12,539
397
8,450
",743
550

13,557
10,785
224
2,258

1,022

2,288

Total from Foreign Countries .

11,231

9,091

6,250

82,314

57,540

30,134

From Canada

2,078

2,012

13

14,503

8,740

58

TOTAL

13,309

11,103

6,263

96,817

66,280

30,192

Mechanical, Wet.
From Sweden
„ Norway . .
„ Other Foreign Countries

8,847
187,386
87

32,014
211,196

46,000
217,933
1,191

27,929
532,942
295

73,203
516,059

100,863
490,949
2,567

Total from Foreign Countries .

196,320

243,210

265,124

561,166

589,262

594,379

From Canada
„ Other British Possessions

48,55i
1,328

72,635
247

71,664

137,789
4,440

169,420
494

157,918

Total from British Possessions .

49,879

72,882

71,664

142,229

169,914

i57,9iS

TOTAL

246,199

316,092

336,788

703,395

759,176

752,297

G. I. C. P O,— No. 1039 I. G. For.— 22-8-1905.— i,ioo.-G. R.

S BOOK IS DUE ON THE LAST DATE
STAMPED BELOW

AN INITIAL FINE OF 25 CENTS

WILL. BE ASSESSED FOR FAILURE TO RETURN
THIS BOOK ON THE DATE DUE. THE PENALTY
WILL INCREASE TO SO CENTS ON THE FOURTH
DAY AND TO Sl.OO ON THE SEVENTH DAY
OVERDUE.

MOV 9 1932
FEB 4 1933

LD 21-50m-8,'32

YD 03880

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